Hollow Sections

The use of steel tubular sections provides for strong, light and profitable structures and as a result offer a host of possibilities in terms of application (expressive capacity). The use of these products also facilitates designs with a greater aesthetic appeal.

Their main advantages are as follows :

Design

• Lighter and more diaphanous structures. Pieces of greater length with fewer joints.
• Large spans. More transparent trusses and purlins with the possibility of eliminating transversal bracing.
• More slender supports. Fewer sections, which can be reduced even more with the use of tubular sections filled with concrete.
• Economical solution. Easily executed direct joints, shorter construction times and easy maintenance, are the results of a correct design and the guarantee of a competitive delivery date and price.
• Expressive capacity. Circular, square, rectangular and elliptical sections, a range of wall thicknesses for every dimension of tubular section, absence of sharp edges,etc. These are the elements that provide innovating, wide ranging possibilities forarchitects and engineers.

Strength

• Compression. For the same centred compression load and under the same conditions tubular sections allow for the use of longer elements than possible should open sections be used. If pillars are involved, a concrete fill permits to reduce further the amount of sections used.
• Torsion. Their stiffness is the highest of all commercial steel sections. For this reason, their behaviour is unbeatable in the case of lateral bulging or warpage.
• Bending. Due to the distribution of material on two axes, their behaviour in bending in two directions, is close to that of a beam and better than that of open sections.
• Tensile. The use of welded joints throughout their extension means that the resistant section in the joints is used completely, unlike bolted joints or those with gusset plates.
• Fatigue. The wide range of mechanical applications in which we can find steel tubular sections are eloquent proof of their perfect behaviour in these conditions.
• Fluid-dynamic. Their low opposition to the thrust of fluids allows lighter sections to be used and makes them the perfect element in outdoor or underwater structures, such as posts, masts, towers, cranes, etc.

Safety
Protecting steel tubular sections by means of surface coating is easier and more economical than open sections due to the absence of cavities and the lower surface area to be covered.

Passive protection:
Structures made from Tubular Sections offer higher fire resistance than open sections due to a lower surface area exposed to fire in relation to mass(lower form factor/mass). Mixed structures based on tubular sections filled with concrete, show excellent behaviour in the presence of fire because of a delay due to the higher thermal inertia.

Active protection:
Filled with water, or when water flows through them due to the thermalsiphon effect, irrigated structures provide almost unlimited fire resistance. Maintenance of water circulation, with the replacement of any losses that might occur due to vaporisation, ensures that the structure is cooled in such a way that gradually the temperature stabilizes at values not very much higher than the water status change temperature and very much lower, therefore, than the critical temperature of steel.
In addition to:

• Introducing longer elements in structures.
• Reducing the number of joints.
• Eliminating struts.
• Stiffeners and plate brackets, to reduce weight.
• A concrete fill increases the surface area per floor.
• Their shape facilitates maintenance and represents an economic solution.